Neurology Resident NC State University Raleigh, NC, United States
Abstract:
Background: Cavalier King Charles Spaniels (CKCS) have a high prevalence of Chiari-like malformation and syringomyelia (CMSM). Dogs with CMSM display signs of neuropathic pain and itch. Imaging findings often do not correlate with severity of signs. Neuropeptides including calcitonin gene related peptide (CGRP) have been implicated in neuropathic pain. Hypothesis: Cerebrospinal fluid (CSF) concentrations of CGRP (C-CGRP) will correlate with CMSM clinical sign severity.Animals: Twentynine CKCS
Methods: CKCS underwent pain and itch quantification by owners (questionnaires) and investigators (physical examination), a brain and cervical spine MRI, and lumbar CSF collection. CSF was frozen to -80oF. C-CGRP in CSF were measured using an ELISA assay (MyBiosource,SanDiego, CA). Dogs were grouped by presence of syrinx, pain, and itch, and C-CGRP were compared between groups using Wilcoxon Rank Sum; C-CGRP and owner reported pain score were evaluated using linear regression analysis.
Results: 15/29 CKCS had SM on MRI, 13/29 were painful, and 12/29 were scratching. C-CGRP was significantly higher in painful dogs (median 114.3, range 11.6-238.3 pg/ml) and dogs with itch (111.67, 38.5-234.8 pg/ml) compared to non-painful dogs (72.57pg/ml, 0-266.2 pg/ml) (p=0.025) and dogs without itch (79.7, 0-266.2 pg/ml). There was a significant correlation between owner pain score and C-CGRP (R2=18%, p= 0.033). No significant difference in C-CGRP was noted between SM+ (99, 0-226.6 pg/ml) and SM- (102.2, 5.9-266.2 pg/ml) dogs (p=0.25) .
Conclusions: CSF CGRP concentration is elevated in CKCS exhibiting pain and itch. CGRP may contribute to neuropathic pain in CMSM and could be a target for therapeutic intervention.
